1. Field of the Invention
The present invention relates to coating systems for articles such as vehicle chassis.
2. Description of the Related Art
In an automobile manufacturing plant vehicle chassis are commonly precoated using a coating tank. The coating fluid usually includes paint solids in a fluid carrier such as water. It is common for the vehicle chassis to leave the coating tank with coating fluid accumulated in and trickling down from the chassis' vertical panels.
The coated chassis are then usually directed through an oven along a travel path, during which the coating fluid will commonly flow out and cure as heat is applied. At the same time coating fluid continues to drain and to boil out from recessed areas such as hem flanges and seams leaving an impression of the trickles and drip on the surface of the painted body. As curing and baking of the paint progresses, the impression of any trickles and the built up drips becomes permanent. These drips must be sanded off before subsequent paint layers can be applied. The additional sanding step adds to the cost of painting, and accordingly the overall manufacturing costs of the automobile body.
Moreover, there is a loss in time and efficiency brought about by the need for a closer inspection of the painted surface, and the need for process control and further handling of the automobile body in order to correct flaws in the painted surface which have resulted from such drips.
A possible method for reducing drips would be to extend the drainage time before the coated bodies are transported into the oven, in order to allow more of the drips to naturally fall away from the vehicle bodies before they reach the curing ovens. In order to increase the drainage time on an automated manufacturing line it would be necessary to add additional conveyors to store and transport the bodies between the coating stage and the curing stage. The installation of additional conveyors would result in a large capital expenditure.
It is an object of the present invention to improve the coating process by removing the drips during curing or before curing or both.